Mark

I have a 1984 XJS V12, after approx. 30 miles the brakes lose nearly all
pressure with the pedal travel almost to the floor! They do still stop the
vehicle but it's a bit scary!

It' not an intermittent problem, any ideas?

Thanks,

Mark.

Blake Dodson

Rebuild your master cylinder or.. somehow air has been introduced into
the brake system. Recent work?

Stop driving until it is resolved.

BD

Mark

Hi Blake,

Many Thanks,

Is it likely that it is the Master Cylinder? I don't know.

There's no recent work been done and it has just flown through it's MOT test
with flying colours. I was thinking along the lines of the brakes probably
binding, overheating and the fluid losing viscosity? although it doesn't
appear to be that when spinning the wheels off ground.

It is consistent, 30-35 miles, if there were air in the system surely this
would be a permenant problem. Again, I don't know.

The car is in A1 condition throughout having covered only 48k miles from
new, I know this means nothing re the problem but it has always been Main
Dealer serviced bang on time, every time and they are at a loss as to what
the cause is.

Cheers,

Mark.

"Blake Dodson" <dieinterim@comcast.net> wrote in message
news:1125328006.790799.131810@g44g2000cwa.googlegroups.com...
> Rebuild your master cylinder or.. somehow air has been introduced into
> the brake system. Recent work?
>
> Stop driving until it is resolved.
>
> BD
>

Chris Halpin

I had a similar problem and it turned out that the Master Cylinder was
corroded.
Replace it as soon as possible.
Cheers
Chris

Mark wrote:
> Hi Blake,
>
> Many Thanks,
>
> Is it likely that it is the Master Cylinder? I don't know.
>
> There's no recent work been done and it has just flown through it's MOT test
> with flying colours. I was thinking along the lines of the brakes probably
> binding, overheating and the fluid losing viscosity? although it doesn't
> appear to be that when spinning the wheels off ground.
>
> It is consistent, 30-35 miles, if there were air in the system surely this
> would be a permenant problem. Again, I don't know.
>
> The car is in A1 condition throughout having covered only 48k miles from
> new, I know this means nothing re the problem but it has always been Main
> Dealer serviced bang on time, every time and they are at a loss as to what
> the cause is.
>
> Cheers,
>
> Mark.
>
> "Blake Dodson" <dieinterim@comcast.net> wrote in message
> news:1125328006.790799.131810@g44g2000cwa.googlegroups.com...
>
>>Rebuild your master cylinder or.. somehow air has been introduced into
>>the brake system. Recent work?
>>
>>Stop driving until it is resolved.
>>
>>BD
>>
>
>
>

tes@test.com

could be a crappy flex line expanding after braking a few times.

Chris Halpin wrote:
> I had a similar problem and it turned out that the Master Cylinder was
> corroded.
> Replace it as soon as possible.
> Cheers
> Chris
>
> Mark wrote:
>
>> Hi Blake,
>>
>> Many Thanks,
>>
>> Is it likely that it is the Master Cylinder? I don't know.
>>
>> There's no recent work been done and it has just flown through it's
>> MOT test with flying colours. I was thinking along the lines of the
>> brakes probably binding, overheating and the fluid losing viscosity?
>> although it doesn't appear to be that when spinning the wheels off
>> ground.
>>
>> It is consistent, 30-35 miles, if there were air in the system surely
>> this would be a permenant problem. Again, I don't know.
>>
>> The car is in A1 condition throughout having covered only 48k miles
>> from new, I know this means nothing re the problem but it has always
>> been Main Dealer serviced bang on time, every time and they are at a
>> loss as to what the cause is.
>>
>> Cheers,
>>
>> Mark.
>>
>> "Blake Dodson" <dieinterim@comcast.net> wrote in message
>> news:1125328006.790799.131810@g44g2000cwa.googlegroups.com...
>>
>>> Rebuild your master cylinder or.. somehow air has been introduced into
>>> the brake system. Recent work?
>>>
>>> Stop driving until it is resolved.
>>>
>>> BD
>>>
>>
>>
>>

T.G. Lambach

Suggest you consider the possibility of an exhaust pipe too close to, or
leaking upon, a brake line and so causing the brake fluid to boil -
after driving thirty miles or so. Alternatively, a stuck caliber could
cause the brake on one wheel to drag and so boil the brake fluid after
some distance.

Mark

The Problem was the rear calipers sticking and boiling the fluid!
This has now been resovled after having them overhauld by a local dealer and
alls well!

Many Thanks to everyone

Mark


"T.G. Lambach" <tlambach@comcast.net> wrote in message
news:RZydnd100fKnJYbeRVn-jg@comcast.com...
> Suggest you consider the possibility of an exhaust pipe too close to, or
> leaking upon, a brake line and so causing the brake fluid to boil - after
> driving thirty miles or so. Alternatively, a stuck caliber could cause the
> brake on one wheel to drag and so boil the brake fluid after some
> distance.

Andy

And your main dealer did not pick this up at a service? And it sailed
through an MOT? - the rolling road brake tests are designed to catch just
this.

Actually thinking about it, it comes as little surprise that your main
dealer failed to notice. We probably all have our horrendous stories we
could tell about a Jaguar Main Agent and certainly my experience of them
(1995 x300 and 1987 XJ40) is evidence of their technicians not being the
brightest on the block.

Andy

"Mark" <rcn@ntlworld.com> wrote in message
news:RG0Ve.10492$Y06.167@newsfe2-win.ntli.net...
> The Problem was the rear calipers sticking and boiling the fluid!
> This has now been resovled after having them overhauld by a local dealer
> and alls well!
>
> Many Thanks to everyone
>
> Mark
>
>
> "T.G. Lambach" <tlambach@comcast.net> wrote in message
> news:RZydnd100fKnJYbeRVn-jg@comcast.com...
>> Suggest you consider the possibility of an exhaust pipe too close to, or
>> leaking upon, a brake line and so causing the brake fluid to boil - after
>> driving thirty miles or so. Alternatively, a stuck caliber could cause
>> the brake on one wheel to drag and so boil the brake fluid after some
>> distance.
>
>